Such arrangements are widely used in various branches of industry as well as in medical, pharmaceutical and biotechnological applications.
In many branches of industry, for example in the Pharmaceutical Industry, Biotechnology Industry, and in the Medical Industry, very high standards of hygiene are required. These standards may vary slightly from country to country, but in general, they require that any surfaces of the measurement arrangement which may come in contact with the product can be effectively cleaned and/or sterilized.
Cleaning and/or sterilization of equipment requires time, during which the equipment and the connected piping system cannot be otherwise used. This time is lost for production every time cleaning or sterilization is required, for example due to a change of product or batch. This is very costly, especially when batch times or product cycles are short compared to the time required for cleaning and/or sterilization.
In order to overcome this problem, the use of disposable parts has become more and more widely used in the Pharmaceutical and the Biotechnology Industries as well as in the Medical Industry.
U.S. Pat. No. 7,096,729 B2 for example describes a disposable fluid flow sensor comprising a fluid flow sensor die, which is mounted on a disposable flow channel tube. A flow sensor die comprising a heater and corresponding sensing elements is for example described in U.S. Pat. No. 6,871,537 B1.
U.S. Pat. No. 6,725,726 for example, describes a pressure measurement arrangement for measuring a line pressure of a product using a reusable pressure sensor comprising a measurement diaphragm. In this arrangement the reusable sensor is connected to a disposable element comprising a measurement chamber. This chamber is connected to the pressure line via an inlet and an outlet channel. It comprises a flexible diaphragm which is in close contact with the measurement diaphragm of the reusable pressure sensor, when the sensor is mounted on the disposable element. This type of connecting element is known in medical technology under the term “dome” or “pressure dome”. The line pressure to be measured is transmitted onto the measurement diaphragm of the sensor via the diaphragm of the measurement chamber. The entire element including the measurement chamber is disposed of after use. It is commonly believed, that pressure domes are necessary, in order to provide a contact surface which is large enough to transmit the line pressure onto the measurement diaphragm of the pressure sensor.
Because of the dome shaped form of the measurement chamber, product will get trapped inside the disposable element. Unfortunately, this means that any product that is held up inside the pressure dome or measurement chamber can not be recovered after the measurement. It will be disposed together with the disposable element.
There are many application where line pressure of expensive products needs to be measured. Any product, that cannot be recovered increases the cost. For example, in the purification process of a Biotech Product, the few cubic centimeters of residual product remaining in a pressure dome or measurement chamber, often called “product hold-up”, may be worth in excess of several hundred thousand dollars.